It was at the end of October last year that André Onana is said to have felt unwell and taken a tablet that was prescribed to his wife.

He later tested positive for the banned drug furisemide.

- We had hoped for a conditional sentence or a suspension that was much shorter than these twelve months because it was probably not intended that he would strengthen his body and thereby improve his performance, says sports director Edwin van der Sar in a statement.

Ajax will appeal the ruling to Cas, the sports arbitration tribunal.

Onana has been the Dutch club's first choice in the goal for five seasons and also plays for Cameroon's national team.

CLIP: This is how a doping test works

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This is how a doping test works